1. Field of the Invention
The present invention resides in a process for increasing gasoline yield and quality using a proprietary fluid cracking catalyst comprising a zeolite dispersed in a magnesia-alumina-aluminum phosphate matrix.
Around the turn of the century, motor vehicles in the United States began to appear in increasing numbers and gasoline obtained a degree of marketable value as a refinery product. Shortly thereafter, demand in the United States for motor fuels began to exceed the amount produced from refinery crude-oil runs geared for producing kerosene, fuel oils, etc., which were very much in demand at the time. Since then, the petroleum industry's most prominent problem has been inventing new and more efficient methods to meet the tremendous demand for gasoline without overproducing other petroleum products at the same time.
Due to the continually increasing demand for gasoline and the ever-shrinking supplies of crude cracking stocks, such as gas oils and the like, more attention has recently been directed to the catalytic cracking of heavier charge stocks such as petroleum residuals. These charge stocks, however, suffer from the disadvantage of having high metals content which is concentrated therein during a normal cracking process. The metals tend to deposit on catalysts and decrease the cracking characteristics thereof in a cracking process. The catalysts herein are particularly formulated to increase the gasoline yield and quality (i.e., BTX) from gas oils during a cracking process and additionally to catalytically crack petroleum residuals with high selectivity to gasoline production as well as having improved metals tolerant characteristics. Examples of typical metals which can be present during the cracking process include: nickel, vanadium, copper, chromium and iron.
2. Description of the Prior Art
The use of zeolitic cracking catalysts has become of increased importance in petroleum cracking processes due to the higher activity characteristics of these catalysts (see "Recycle Rates Reflect FCC Advances," by J. A. Montgomery, Oil & Gas Journal, Dec. 11, 1972, pp 81-86).
Several processes have been proposed in the past wherein zeolite catalysts are utilized to crack crude oils and petroleum residual feedstocks.
For example, U.S. Pat. No. 3,617,528; entitled "Hydrotreating Process and Catalyst;" issued to Hilfman on Nov. 2, 1971 discloses a hydrotreating process and a catalyst consisting of an alumina containing porous carrier material, a nickel component and a phosphorus component. The porous carrier is described as an adsorptive high surface area support. Suitable carrier materials include amorphous refractory inorganic oxides, for example, alumina, titania, zirconia, chromia, magnesia and the like.
U.S. Pat. No. 3,838,040; entitled "Hydrocracking with Zeolite in a Silica-Magnesia Matrix," issued to Ward on Sept. 24, 1974 relates to hydrocarbon conversion catalysts which are described as having increased activity and selectivity as well as improved physical characteristics. The catalysts consist of crystalline zeolitic aluminosilicates and silica-magnesia. It is to be noted that the prior art fails to appreciate the catalyst combination disclosed herein.